1. Field of the Invention
This invention relates in general to a modular data storage system, and more particularly to a process and apparatus for securing a data storage module within an enclosure to reduce mechanical shock and vibrations associated therewith during operation, handling and transportation.
2. Description of the Related Art
In general, a common data storage system comprises multiple data storage modules that slidably dock within an enclosure. Normally, the data storage modules provide disk drives which each includes a plurality of internal disks or platters that spin at high speeds within the drive during operation. Although there are numerous data storage modules and enclosures used in the industry today, none satisfy all of the performance requirements that the industry demands.
As illustrated in FIG. 1, a conventional data storage system 8 includes an enclosure 10 having multiple bay slots 12 that extend linearly from the front of the structure to a backplane where a circuit board 14 is mounted. The circuit board provides various multiple pin connectors 16 and circuitry on a silicon composite sheet of about 1.5 mm thick. Each bay slot 12 provides a set of upper and lower guide tracks 18 to aid the user in aligning the data storage module 20 within the desired bay slot 12. Each guide track 18 provides a width Wt.
A typical data storage module 20 consists of a drive tray 32, a securing mechanism 34, guide rails 36, and a data storage device 22, e.g. a disc drive. The drive tray 32 provides a rigid rectangular structure for receiving, securing, and mounting the disc drive. The securing mechanism 34 attaches to the front end of the drive tray 32 so that the user can lock each data storage module 20 in the desired bay slot 12 of enclosure 10. As illustrated, guide rails 36 reside on either side of the drive tray 32 and provide the necessary structure to be received by the guide tracks 18 of the enclosure slot 12. Each guide rail 36 provides a constant width Wr and thickness between distal ends.
The above data storage system is very popular in the industry due to its simplicity in design, ease of operation, and relatively low cost to produce. However, the conventional design has problems inherent to its construction during operation. In particular, the system provides a certain amount of designed gap between the guide rails 36 and the supporting guide tracks 18, and between the locking mechanism 34 and the enclosure 10. Because these gaps ensure ease of insertion and removal of the modules and manufacturability of the parts, they can not be eliminated. Consequently, a conventional data storage module is essentially free to move across the gaps, even after the conventional latching mechanism is locked.
This free boundary condition existing along the gaps, together with the large mass of a typical data storage device, make the module easily excited by shock and vibration regardless of whether they are self-generated by the data storage device or externally imparted upon the system. Consequently, while the rear end of a module is constrained in all three translational axes by the circuit board connector, the front end of the module is not well constrained. Therefore, this arrangement inherently forces the module to rotate about its better constrained end, the connector, in response to vibration, shock excitation, and gyroscopic motion, even when the force is translational. In other words, disc drives in the conventional data storage system are prone to rotational vibrations regardless of whether the input is external to the drive or self-exited by the drive itself during operation, handling and transportation.
Rotational vibration is an increasing concern to a data storage systems designer since it can have a significant impact on the performance and data integrity of modern disc drives. In addition, considering that the rotational speed and data track density of the disc drive will continue to rapidly increase in the future and disc drive manufacturers have very limited options to reduce or suppress the rotational vibrations at the drive level, the current problems exhibited by rotational vibrations will only get worse over time if no viable solutions are developed.
In attempts to resolve the above problems, some conventional data storage systems utilize elastomeric shock mounts to isolate or attenuate the shock and vibrations externally imparted upon the system. However, for the shock mounts to work properly, they must be allowed to deflect freely and therefore require extra sway and component space within the system. Such a system fails to achieve the maximum data storage density for the given data storage device, and provides an additional cost and process assembly step. In addition, given that the rotational vibrations may be caused by the forces that the drive itself generates, such as disk stack imbalance and the reaction from the actuator seek, the shock mounts fail to isolate or attenuate the rotational vibrations.
Other conventional data storage systems attempt to provide data storage module constraints inside the enclosure. These constraints are designed to rely on contacts between rigid members and non-compliant parts of the enclosure, and therefore do not take-up, fill, or effectively remove the gaps between the mating parts that allow for the rotational vibrations. For example, compliant members near the rear end of the enclosure between the data storage module and the enclosure. Consequently, such designs fail to effectively constrain the movement of the data storage modules in more than one direction.
Due to the problems inherent to the conventional data storage system, data storage devices in such systems are susceptible to shock and vibrations imparted upon the system during the transportation, end-use handling, and operation, and often sustain permanent physical damages or loss of data. In addition, disc drives in the conventional data storage system are very sensitive to the effect of rotational vibration and may suffer significant degradation of performance during the normal operation of the system.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.